Speed sensors, or detectors of various types are well known in the art. In recent years the application of speed detection to motor control functions has stimulated demands on the sophistication of those sensors. Rotational speed sensors are commonly configured in the same manner as an electric machine, for example, a coil is placed in proximity to rotating magnets whereby the magnetic field induces a voltage on the passing coil in accordance with Faraday's Law. The rotating permanent magnets induce a voltage on the coil and ultimately a voltage whose frequency and magnitude are proportional to the rotational speed of the passing magnets.
Many of the tachometers that are currently available in the art exhibit a trade off between capabilities and cost. Those with sufficient resolution and accuracy are often very expensive and perhaps cost prohibitive for mass production applications. Those that are inexpensive enough to be considered for such applications are commonly inaccurate or provide insufficient resolution or bandwidth for the application. Thus, there is a need, in the art for a low cost robust tachometer that provides sufficient accuracy and resolution for motor control applications and yet is inexpensive enough to be cost effective in mass production.